If the mortality rate seems high we must realize that Nature is a ruthless teacher. There are no second chances in Mother Nature's Survival Course.

William S. Burroughs

The curse of mortality. You spend the first portion of your life learning, growing stronger, more capable. And then, through no fault of your own, your body begins to fail. You regress. Strong limbs become feeble, keen senses grow dull, hardy constitutions deteriorate. Beauty withers. Organs quit. You remember yourself in your prime, and wonder where that person went. As your wisdom and experience are peaking, your traitorous body becomes a prison.

Brandon Mull

Yet human intelligence has another force, too: the sense of urgency that gives human smarts their drive. Perhaps our intelligence is not just ended by our mortality; to a great degree, it is our mortality.

Adam Gopnik

Each of us is merely a small instrument; all of us, after accomplishing our mission, will disappear.